This invention relates to an electrical connector to be connected to a cable and a method for connecting the cable to the connector.
As well known, various kinds of signals are transmitted and received through cables between electronic appliances, for example, between a personal computer and peripheral equipment, and occasionally driving power may be supplied from the personal computer to the peripheral equipment by the use of the same cable.
One example of such a cable is shown in FIGS. 31 and 32. The cable 100 shown in FIGS. 31 and 32 comprises a pair of forward direction signal wires 111a and 111b for feeding signals from the personal computer to the peripheral equipment and a pair of backward direction signal wires 112a and 112b for returning signals from the peripheral equipment to the personal computer. The signal wires 111a and 111b and 112a and 111b are respectively twisted together and covered with aluminum tapes 113 wound therearound and further covered with individual shield braids 114. These signal wires 111a, 111b, 112a and 112b are twisted together with a pair of power supply wires 115a and 115b (one of supply wires may be a bare wire) and a bare drain wire 116 to form a cable core 110.
By these twisting treatments, the drain wire 116 (including a bare wire if one of the power supply wires 115a and 115b is the bare wire) is brought into close contact with the individual shield braids 114 of the signal wires to be electrically contact with the shield braids.
Thereafter, the cable core 110 thus constructed is covered with a metal laminate tape 117 consisting of an aluminum foil on one side and a plastic insulating layer on the other side and wound on the cable core 110. The laminate tape 117 is further covered with an outer shield braid 118 and a sheath 119 of a plastic insulating material.
In connecting the personal computer and the peripheral equipment by means of a cable constructed as described above, in general, one end of the cable 100 is connected to an electrical connector which is then mounted in part (connector mounting portion) of the personal computer or peripheral equipment. In practically connecting the cable 100 and the electrical connector, first the shield braids or the like of the cable 100 at the cable end are partially removed to exposed ends of the wires which are then connected to connecting terminals (contacts) of the electrical connector by soldering, crimping (by collapsing metal pieces or sleeves) or piercing wires with knife edges of grooves of the contacts.
With such a connection between the cable and the connector described above, no problems occur, when it is satisfied with transmission characteristics at normal levels. However, in order to obtain transmission characteristics with higher accuracy for use within a range of higher frequencies, it has been a found by the research of the inventors of the present application that more careful precautions are required in connecting the cable and the electrical connector.
In more detail, even if the construction of a cable itself is substantially complete in transmission characteristics, deterioration in transmission characteristics is unavoidable unless the connection is effectively performed. It has been found that if the connection is not effectively performed, any transmission characteristics could not be sufficiently utilized no matter how a cable is superior as the cable 100 shown in FIGS. 31 and 32.
In view of this, the inventors have further earnestly investigated the connection between the cable and the connector, as a result of which the following facts have been clarified.
(1) In the past, when internal wires were taken out after partial removal of shield braids of a cable, any strict examination on wiring lengths of the wires was not effected for use at the normal level of transmission characteristics. For example, when employing the soldering or crimping described above, it is required to lengthen the wires to a certain extent owing to its construction. However, the longer the wires, the longer becomes the mismatching portion of impedance. PA0 (2) In the past, moreover, with a tape cable, respective wires were dispensed in a relatively accurately, while on the other hand with a circular cable having longitudinally twisted wires mingled with one another for example as the cable 100 shown in FIGS. 31 and 32, the wires were often crossed or entangled with one another and directed in irregular directions because of no strict consideration in wiring for connecting the wires to contacts of an electrical connector. As a result, the cross talk and transmission losses were not avoided. PA0 (3) Moreover, even if the shielding between the signal wires of a cable and the shielding of the cable as a whole are complete in order to prevent any occurrence of cross talk or the like, the cross talk may occur if the shielding in an electrical connector to be connected to the cable should not be complete. PA0 (1) As the shield plate is provided between at least one set of adjacent contacts in the housing according to the invention, the cross talk can be effectively prevented even if the connector is connected with a cable, for example, whose a pair of forward direction signal wires and a pair of backward direction signal wires are mingled with each other. Moreover, when the shield plate is ground, a good shield effect can be obtained. PA0 (2) When the electrical connector according to the invention is combined with a cable provided with individual shield braids for shielding the respective signal wires and provided with an outer shield braid for shielding the entire cable, the occurrence of the cross talk can be effectively prevented even in the case using in the zone of higher frequencies. In other words, the electrical connector according to the invention causes the cable to exhibit its transmission characteristics sufficiently. PA0 (3) Moreover, as the contacts received in the housing have the knife-edged grooves at their leading connection portions according to the invention, the piercing connection can be achieved in a simple manner only by forcing the wires with insulating covers to the connection portion when connecting the wires of the cable to the connector. Therefore, the troublesome operation for partially removing insulating layers of fine wires of a cable is not needed, thereby obtaining a good operation efficiency. Furthermore, as the contact exclusive for the drain wire is provided in the connector according to the invention, the piercing connection of the bare wire is also simply accomplished at the same time when the other wires are connected. PA0 (4) As the wire distribution block for dividing the wires of the cable in two directions is used in connecting them to the contacts in the housing according to the invention, the wiring length of the wires can be made shortest, as a result of which the mismatching portion of impedance or the like can be suppressed to a minimum length. Moreover, the wiring divided into two directions described above eliminates the crossed wiring and entangled wiring so that the wires are fixed in rectilinear and uniform wiring, with the result that the cross talk and transmission losses can be effectively prevented.